A remotely actuated door lock can be strike-centered, that is have its actuating mechanism in the strike on the doorjamb or in the lock on the door. Such a strike-centered lock has the disadvantage that it is fairly difficult to retrofit the door with the bulky strike mechanism, and such systems are normally easy to jimmy and otherwise circumvent.
There are many types of door-mounted locks. They may be incorporated in the doorknob assembly, as in U.S. Pat. No. 4,073,527 of Schlage. In another such arrangement as described in U.S. Pat. No. 2,763,888 of Billeter, a pneumatic door-mounted door closer is connected to a pneumatic actuator in a lock mechanism to withdraw the bolt momentarily as the door is just about closed, so that the door bolt does not noisily engage the strike. In U.S. Pat. No. 3,234,766 of O'Brien a small rotary output motor carries a worm on its output shaft that meshes with a gear-sector paul that operates the latch bolt. It is not structured to, or include backset choices, or include the bolt, crosspiece fin, plunger practically one piece assembly, held rigidly together directly in one axis line for greater efficiency and durability. Similarly, U.S. Pat. Nos. 3,576,119 and 3,751,086 of Harris and Geringer, respectively, have a solenoid mounted directly on the door. In U.S. Pat. No. 3,890,608 of Peterson the solenoid is linked to the bolt. A system kinematically identical to that of Peterson is seen in U.S. Pat. No. 4,169,616 also of Peterson which uses a pneumatic actuator.
All such arrangements are fairly bulky, making it impossible to mount them on the inside surface of the thin (narrow) stile of a standard metal-and-glass entrance door of the type used in shops and offices, etc., in such a manner that it can be actuated from outside the door by a standard rim key cylinder. A partial solution to this problem of retrofitting an existing (narrow) thin-stile door is proposed in U.S. Pat. No. 4,099,752 of Geringer. The mechanism of this arrangement is extremely complex, however.
With all these arrangements manual actuation of the lock is frequently impossible, and it is often also impossible to cut out the lock by holding it in a position with its bolt fully retracted. What is more, such locks are normally only set up for one particular type of installation, for instance, an in-swinging door; they cannot be adapted at the site to different setups. the Savarieau et al. and Bright references basically are to latch or fasten the door in a locked position rather than for an alternate to keep a door unlocked, and do not employ the bolt, crosspiece fin, plunger assembly structure. Curtiss et al. and Flodell's strikes do not use one part of the assembly for outswing doors and another means of the assembly for inswing doors, etc., and Rifkin, Hamilton, Cleff, Rau, Spinello, Ewing; Pond and Nikolaus have their relative differences too.
Note, O'Brien's 82 is a threaded member which engages mounting plate 28 and rear housing plate 16 the latter being locked in place by a key 84. It appears that 86 is a shaft on the other side connected to handle 90 and cam 88 and to reiterate O'Brien's invention is mainly a motor driven unit with added solenoid and with mechanical apparatus workings of a different character and different objective than of this present invention of backset choices and bolt, crosspiece fin, and plunger assembly structures, etc.
The other principal disadvantage of such locks is that they must be made in many different models to accommodate different features, depending on security requirements.